Deflectable medical devices

ABSTRACT

Medical devices and methods for making and using medical devices are disclosed. An example medical device may be a deflectable medical device that includes a catheter shaft having a distal end. An ablation electrode may be disposed at the distal end. A deflection mechanism may be coupled to the catheter shaft. The deflection mechanism may include a deflection body and a pull wire coupled to the deflection body. The deflection body may have a longitudinally-extending furrow formed therein. A flex member may be disposed adjacent to the deflection mechanism.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority under 35 U.S.C. §119 to U.S.Provisional Application Ser. No. 61/548,582, filed Oct. 18, 2011, theentirety of which is incorporated herein by reference.

TECHNICAL FIELD

The present disclosure pertains to medical devices, and methods formanufacturing medical devices. More particularly, the present disclosurepertains to deflectable medical devices and methods for manufacturingand using such devices.

BACKGROUND

A wide variety of intracorporeal medical devices have been developed formedical use, for example, intravascular use. Some of these devicesinclude guidewires, catheters, and the like. These devices aremanufactured by any one of a variety of different manufacturing methodsand may be used according to any one of a variety of methods. Of theknown medical devices and methods, each has certain advantages anddisadvantages. There is an ongoing need to provide alternative medicaldevices as well as alternative methods for manufacturing and usingmedical devices.

BRIEF SUMMARY

The invention provides design, material, manufacturing method, and usealternatives for medical devices. An example medical device may be adeflectable medical device that includes a catheter shaft having adistal end. An ablation electrode may be disposed at the distal end. Adeflection mechanism may be coupled to the catheter shaft. Thedeflection mechanism may include a deflection body and a pull wirecoupled to the deflection body. The deflection body may have alongitudinally-extending furrow formed therein. A flex member may bedisposed adjacent to the deflection mechanism.

Another example medical device may be a deflectable medical device forablating renal artery nerves. The medical device may include a cathetershaft including a proximal shaft portion, a deflection body coupled tothe proximal shaft portion, a flex member coupled to the deflectionbody, and an ablation member coupled to the flex member. The deflectionbody may include a first longitudinally-extending spine, a secondlongitudinally-extending spine, a first set of ribs disposed between thefirst spine and the second spine, and a first furrow disposed along thefirst set of ribs. An actuation member may be coupled to the deflectionbody. The actuation member may be configured to shift the catheter shaftbetween a first straightened configuration and a second curvedconfiguration. The actuation member may be disposed within the firstfurrow.

Another example deflectable medical device may include a catheter shafthaving a distal end. An ablation electrode may be disposed at the distalend. A deflection mechanism may be coupled to the catheter shaft. Thedeflection mechanism may include a support coil, a biasing member, and apull wire. The deflection mechanism may be configured to shift thecatheter shaft between a first straightened configuration and a secondcurved configuration. A tubular member may be disposed adjacent to thedeflection mechanism. The tubular member may have a plurality of slotsformed therein.

The above summary of some embodiments is not intended to describe eachdisclosed embodiment or every implementation of the present invention.The Figures, and Detailed Description, which follow, more particularlyexemplify these embodiments.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention may be more completely understood in consideration of thefollowing detailed description of various embodiments of the inventionin connection with the accompanying drawings, in which:

FIG. 1 is a schematic view illustrating an example renal nervemodulation system;

FIG. 2 is a schematic view illustrating the location of the renal nervesrelative to the renal artery;

FIG. 3 is a partially cut away side view of a portion of an examplecatheter;

FIG. 4 is a partial cross-sectional side view of an example catheterdisposed within a body lumen;

FIG. 4A is a partial cross-sectional side view of another examplecatheter disposed within a body lumen;

FIG. 5 is a perspective view of a portion of an example flex body;

FIG. 6 is a partially cut away side view of a portion of an examplecatheter;

FIG. 7 is a plan view for an example catheter;

FIG. 8 is a partially cut away side view of an example catheter;

FIG. 9 is a perspective view of a portion of an example flex body;

FIG. 10 is a plan view for an example catheter;

FIG. 11 is a side view of an example flex body;

FIG. 12 is a side view of an example flex body;

FIG. 13 is a side view of an example flex body;

FIG. 14 is a side view of an example flex body; and

FIG. 15 is a partially cut away side view of an example catheter.

While the invention is amenable to various modifications and alternativeforms, specifics thereof have been shown by way of example in thedrawings and will be described in detail. It should be understood,however, that the intention is not to limit the invention to theparticular embodiments described. On the contrary, the intention is tocover all modifications, equivalents, and alternatives falling withinthe spirit and scope of the invention.

DETAILED DESCRIPTION

For the following defined terms, these definitions shall be applied,unless a different definition is given in the claims or elsewhere inthis specification.

All numeric values are herein assumed to be modified by the term“about,” whether or not explicitly indicated. The term “about” generallyrefers to a range of numbers that one of skill in the art would considerequivalent to the recited value (i.e., having the same function orresult). In many instances, the terms “about” may include numbers thatare rounded to the nearest significant figure.

The recitation of numerical ranges by endpoints includes all numberswithin that range (e.g. 1 to 5 includes 1, 1.5, 2, 2.75, 3, 3.80, 4, and5).

As used in this specification and the appended claims, the singularforms “a”, “an”, and “the” include plural referents unless the contentclearly dictates otherwise. As used in this specification and theappended claims, the term “or” is generally employed in its senseincluding “and/or” unless the content clearly dictates otherwise.

The following detailed description should be read with reference to thedrawings in which similar elements in different drawings are numberedthe same. The drawings, which are not necessarily to scale, depictillustrative embodiments and are not intended to limit the scope of theinvention.

It is noted that references in the specification to “an embodiment”,“some embodiments”, “other embodiments”, etc., indicate that theembodiment described may include a particular feature, structure, orcharacteristic, but every embodiment may not necessarily include theparticular feature, structure, or characteristic. Moreover, such phrasesare not necessarily referring to the same embodiment. Further, when aparticular feature, structure, or characteristic is described inconnection with one embodiment, it should be understood that suchfeature, structure, or characteristic may also be used connection withother embodiments whether or not explicitly described unless clearlystated to the contrary.

Certain treatments may require the temporary or permanent interruptionor modification of select nerve function. One example treatment is renalnerve ablation which is sometimes used to treat conditions related tohypertension and/or congestive heart failure. The kidneys produce asympathetic response to congestive heart failure, which, among othereffects, increases the undesired retention of water and/or sodium.Ablating some of the nerves running to the kidneys may reduce oreliminate this sympathetic function, which may provide a correspondingreduction in the associated undesired symptoms.

Many nerves (and nervous tissue such as brain tissue), including renalnerves, run along the walls of or in close proximity to blood vesselsand thus can be accessed intravascularly through the walls of the bloodvessels. In some instances, it may be desirable to ablate perivascularnerves using a radio frequency (RF) electrode. In other instances, theperivascular nerves may be ablated by other means including applicationof thermal, ultrasonic, laser, microwave, and other related energysources to the vessel wall.

Because the nerves are hard to visualize, treatment methods employingsuch energy sources have tended to apply the energy as a generallycircumferential ring to ensure that the nerves are modulated. However,such a treatment may result in thermal injury to the vessel wall nearthe electrode and other undesirable side effects such as, but notlimited to, blood damage, clotting, weakened vessel wall, and/or proteinfouling of the electrode.

While the devices and methods described herein are discussed relative torenal nerve modulation through a blood vessel wall, it is contemplatedthat the devices and methods may be used in other applications wherenerve modulation and/or ablation are desired. The term modulation refersto ablation and other techniques that may alter the function of affectednerves.

FIG. 1 is a schematic view of an example renal nerve modulation system10 in situ. System 10 may include a renal ablation catheter 12 and oneor more conductive element(s) 14 for providing power to catheter 12. Aproximal end of conductive element(s) 14 may be connected to a controland power element 16, which supplies necessary electrical energy toactivate one or more electrodes (e.g., electrode 24 as shown in FIG. 3)disposed at or near a distal end of catheter 12. When suitablyactivated, the electrodes are capable of ablating adjacent tissue. Theterms electrode and electrodes may be considered to be equivalent toelements capable of ablating adjacent tissue in the disclosure whichfollows. In some instances, return electrode patches 18 may be suppliedon the legs or at another conventional location on the patient's body tocomplete the circuit.

Control and power element 16 may include monitoring elements to monitorparameters such as power, temperature, voltage, amperage, impedance,pulse size and/or shape and other suitable parameters, with sensorsmounted along catheter, as well as suitable controls for performing thedesired procedure. In some embodiments, power element 16 may control aradio frequency (RF) electrode. The electrode may be configured tooperate at a frequency of approximately 460 kHz. It is contemplated thatany desired frequency in the RF range may be used, for example, from450-500 kHz. It is further contemplated that additionally and/or otherablation devices may be used as desired, for example, but not limited toresistance heating, ultrasound, microwave, and laser devices and thesedevices may require that power be supplied by the power element 16 in adifferent form.

FIG. 2 illustrates a portion of the renal anatomy in greater detail.More specifically, the renal anatomy includes renal nerves RN extendinglongitudinally along the lengthwise dimension of renal artery RA andgenerally within or near the adventitia of the artery. The human renalartery wall is typically about 1 mm thick of which 0.5 mm is theadventitial layer. As will be seen in the figure, the circumferentiallocation of the nerves at any particular axial location may not bereadily predicted. Nerves RA are difficult to visualize in situ and sotreatment methods may desirably rely upon ablating multiple sites toensure nerve modulation.

FIG. 3 is a partially cut away side view of catheter 12. Here, some ofthe structural features of catheter 12 can be seen. For example,catheter 12 may include a catheter shaft 20. Catheter shaft 20 may takethe form of a metallic and/or polymer shaft and may includevisualization (e.g., marker bands) and/or reinforcing structures (e.g.,braids, coils, etc.) commonly used for catheter shafts. In at least someembodiments, catheter shaft 20 may form or define an outer surface ofcatheter 12. An ablation member or electrode 24 may be attached tocatheter shaft 20. Ablation member 24 may be formed at or otherwise forma distal tip of catheter shaft 20. In general, ablation member 24 may beconfigured to ablate target tissue at or near a body lumen. For example,ablation member 24 may be used to ablate a renal nerve adjacent to arenal artery. Ablation member 24 may vary and may include a number ofstructures such as a plurality of wires (e.g., two wires) that connectwith electrode wire 14 and, ultimately, control and power element 16.Electrode wire 14 may be soldered to a side slot on the ablation member24, for example.

Ablation member 24 may also include other structures and/or featuresassociated typically associated with ablation (e.g., thermal ablation)such as a temperature monitoring member 22, which may take the form of athermocouple or thermistor. In at least some embodiments, a thermistorincluding two thermistor wires may be disposed adjacent to ablationmember 24. In some embodiments, the wires are not physically connectedto ablation member 24. The thermistor wires may terminate in the centerbore of the ablation member 24 and may be potted with a thermallyconducting epoxy in a plastic tube which is then glued to the bore ofthe ablation member 24.

When conducting a medical procedure that involves ablation, it may bedesirable to place the ablation member (e.g., ablation member 24) nearthe target tissue so as to ablate the target while minimizing damage tonon-targeted tissue. In order to more specifically place or steercatheter 12 to a position adjacent to the intended target, catheter 12may be configured to be deflectable. Accordingly, catheter 12 mayinclude a tubular member 26 that includes a flex body 28 that can beselectively bent. This allows a user to orient, for example, ablationmember 24 in a desirable position within a body lumen. To effectdeflection, one or more pull wires or actuation members 30 a/30 b may becoupled to flex body 28. This allows a user to actuate (e.g., “pull”)one or both of wires 30 a/30 b to deflect flex body 28 and, thus,catheter 12 (e.g., ablation member 24). In addition, wires 30 a/30 b maybe stiff enough so that they can also be used to provide a pushing forceon flex body 28 to, for example, straighten flex body 28. In the exampleillustrated in FIG. 3, the actuation member takes the form of acontinuous wire that is looped through or otherwise coupled to a distalend of flex body 28 so as to define a pair of wire sections (e.g., wires30 a/30 b). Other embodiments are contemplated, however, includingembodiments where the actuation member includes a plurality ofindividual wires that are attached, for example, to the distal end offlex body 28.

To further aid in properly orienting catheter 12 within a body lumen, aflex tube 32 may be coupled to flex body 28 (e.g., at a distal end offlex body 28). Flex tube 32 may have a plurality of slots 34 formedtherein. In general, flex tube 32 is configured to be flexible so thatthe distal portion of catheter 12 (e.g., adjacent to ablation member 24)can bend upon encountering the wall of a body lumen. Accordingly, flextube 32 can bend when/if ablation member 24 engages the wall of the bodylumen during deflection of flex body 28 so that ablation member 24 mayatraumatically follow along the wall of the body lumen.

In at least some embodiments, flex body 28 and flex tube 32 are twodistinct structures that are attached to one another. In otherembodiments, flex body 28 and flex tube 32 are formed in tubular member26 by selectively cutting the desired pattern into tubular member 26.For example, tubular member 26 may be cut in a first pattern thatdefines flex body 28 and tubular member 26 may be cut in a secondpattern that defines flex tube 32. The cut patterns may be substantiallycontinuous (e.g., where relatively little or no appreciable spacing isdefined between the patterns) or the patterns may be longitudinallyspaced so that a gap is defined therebetween. Analogously, flex body 28and flex tube 32 may be substantially continuous with one another orlongitudinally spaced from one another.

At a proximal end of flex body 28, a coil 36 may be coupled to flex body28. Attachment between flex body 28 and coil 36 may be accomplished in anumber of different manners. For example, flex body 28 may be directlyattached to coil 36. Alternatively, a coupler member 38 may be attachedto the proximal end of flex body 28 and coil 36 may be attached tocoupler member 38. These are just examples. A variety of differentstructures and/or arrangements may be utilized without departing fromthe spirit of the invention.

Catheter 12 may also include a number of additional features commonlyassociated with medical devices. For example, catheter 12 may includeradiopaque markers or bands, additional or alternative catheter shaftconstructions (e.g., having lumens, reinforcements, balloons, or othercatheter structures), a proximal hub and strain relief, and the like.

FIG. 4 illustrates catheter 12 disposed in a blood vessel 40. Here itcan be seen how flex body 28 (and flex tube 32) can aid in theorientation of catheter 12 within blood vessel 40. In this example, pullwire 30 a may be actuated to cause flex body 28 to bend. This bendsablation member 24 toward the wall of blood vessel 40. Flex tube 32allows catheter 12 to further bend so that ablation member 24 can tracealong and lay flat against the wall of blood vessel 40. However, otherembodiments are also contemplated that allow the tip of the electrode 24to touch the wall of blood vessel 40 rather than lay flat against thewall. For example, FIG. 4A illustrates catheter 12′ that may be similarin form and function to other catheters disclosed herein. Catheter 12′may lack flex tube 32. This allows the tip of electrode 22 to contactthe wall of blood vessel 40. In some embodiments, the tip of electrode22 may be insulated but thermally conductive and energy may be emittedfrom a point proximal of the tip. This may allow the ablation point ofthe electrode to be spaced from or otherwise positioned away from thevessel wall and may also improve heat dissipation at the point ofelectrode 22 contact, which may reduce potential thermal damage to theinterior vessel wall.

FIG. 5 illustrates flex body 28 and some of the additional structuralfeatures contemplated for flex body 28. For example, flex body 28 mayinclude a pair of longitudinally-extending spines 42 a/42 b. In someembodiments, spines 42 a/42 b are disposed on opposite sides of flexbody 28. However, other embodiments are contemplated where spines 42a/42 b have a different distribution and/or where flex body 28 includesa different number of spines (e.g., more or less). Between spines 42a/42 b, a plurality of slots 44 a/44 b may be formed in flex body 28that define a plurality of ribs 46 a/46 b. In general, each of the ribs46 a/46 b extend between adjacent spines 42 a/42 b.

One or more furrows, for example furrows 48 a/48 b, may be formed alongribs 46 a/46 b. Furrows 48 a/48 b may generally take the form ofindentations or dimples that extend longitudinally along flex body 28.Furrows 48 a/48 b may be formed in any suitable way. For example, insome embodiments, flex body 28 may be made from a shape memory and/orsuper elastic material such as a nickel-titanium alloy (e.g., nitinol).In these embodiments, flex body 28 may be deformed into the desiredshape, for example using a suitably shaped fixture, and flex body 28 maybe heat set to the desired shape. In other embodiments, a fixture ortool may be used to bend or deform into the desired shape. Furrows 48a/48 b may house pull wire sections 30 a/30 b as shown in FIG. 6. Assuch, a user may actuate pull wire section 30 a to deflect catheter 12in a first direction A and a user may actuate pull wire section 30 b todeflect catheter 12 in a second direction B as shown in FIG. 7. To aidin deflection, a user may also push with the opposite wire (e.g., todeflect in direction A, a user may pull on pull wire section 30 a whilepushing on pull wire section 30 b). Some embodiments of flex body 28 maylack furrows 48 a and/or 48 b. In some of these and in otherembodiments, pull wire sections 30 a/30 b may extend along the exteriorof flex body 28, along the interior of flex body 28, through anotherstructure disposed adjacent to (e.g., along the exterior, along theinterior, etc.) flex body 28, or have any other suitable positioning.

In some embodiments, a plurality of pull wires or pull wire sections 30a/30 b may be used. However, in some embodiments, only a single pullwire 30 may be used as shown in FIG. 8. In these embodiments, flex body28 may be formed with only a single furrow (e.g., furrow 48 a) to housepull wire 30. However, flex body 28 may just as easily have a pair offurrows 48 a/48 b (e.g., where one of the furrows 48 a/48 b is “empty”)or any other suitable configuration.

FIG. 9 illustrates another example flex body 128. Flex body 128 mayinclude a singular longitudinally-extending spine 142. Just like in flexbody 28, cuts 144 may be formed in flex body 128 that define ribs 146.Furrow 148 may extend along ribs 146 and form a location that housespull wire 130. Flex body 128 may function similarly to other flex bodiesdisclosed herein. For example, FIG. 10 illustrates that a user mayactuate pull wire 130 to deflect catheter 112 in direction C. Catheter112 may return to the “undeflected” configuration by pushing on pullwire 130 and/or via elastic recovery of flex body 128.

FIGS. 11-14 illustrate variations that are contemplated for any of theflex bodies disclosed herein. In general, these variations may be usedwith any of the flex bodies disclosed herein. For example, in FIG. 11 anexample flex body 228 is shown having slots 244 and ribs 246. Spine 242has a width W. In contrast, FIG. 12 shows flex body 228′ having slots244′, ribs 246′, and spine 242′. Spine 242 has a width W′, which isdifferent from width W. Collectively, these figures illustrate that avariety of spine widths are contemplated for any of the flex bodiesdisclosed herein. In general, as the width of the spine narrows, lessforce is required to deflect the flex body. However, such flex bodiesmay have less elastic recovery force to return to a straightenedconfiguration (e.g., if an actuation member is not used to “push” theflex body straight). Conversely, a wider spine may require greater forceto deflect but has more elastic recovery. In addition, a flex body witha wider spine may also transmit torque along its length moreefficiently. In some interventions it may be desirable to utilize a flexbody having enhanced flexibility (e.g, smaller spine widths) and inother interventions it may be desirable to utilize a flex body withenhanced stiffness (e.g., larger spine widths). Accordingly, variabilityin the width of the spine allows a variety of different flex bodies tobe manufactured with characteristics that are tailored to the particularintervention.

FIG. 13 illustrates another example flex body 328. Flex body 328includes slots 344 and ribs 346. In this embodiment, the width of spine342 tapers. Accordingly, a first region 342 a of spine 342 has adifferent width than a second region 342 b. Tapering the width of spine342 may be desirable for a number of reasons. For example, a taperedspine 342 may provide a smooth transition in flexibility that allows theflexural properties of flex body 328 to be more closely matched withthose of adjacent structures. This may help reduce kinking

FIG. 14 illustrates another example flex body 428. Flex body 428includes slots 444 and ribs 446. In this example, spine 442 may have afirst region 442 a, a second region 442 b, and a third region 442 cdisposed between regions 442 a/442 b. The spine width along first region442 a and along second region 442 b are generally larger than alongthird region 442 c. This may define an “hour glass” shape orconfiguration for spine 442 with a region (e.g., third region 442 c)with greater flexibility.

In addition to what is disclosed herein, a variety of additional flexbodies are contemplated where the width of the spine varies differentlyfrom what is shown. For example, a step taper in spine width may beutilized. Alternatively, a linear taper, a non-linear taper, a parabolictaper, a curved or curvilinear taper, or the like may be utilized. Inaddition, a variety of slot variations/configuration may be utilizedincluding those variations disclosed herein. Furthermore, tubular member26 (or any other tubular member that includes the various flex bodiesand/or flex tubes disclosed herein) may be selectively heat treatedalong a portion of the length thereof to temper or otherwise alter themechanical properties of the material. These are just examples.

FIG. 15 illustrates another example catheter 512. Catheter 512 includescatheter shaft 520. Ablation member 524 may be coupled to catheter shaft520. Catheter 512 includes a deflection member 548, which takes the formof a coil. Deflection member 548 may be bonded to or otherwise coupledwith catheter shaft 520 and/or flex body 532. A tension wire 550 may becoupled to coil 548. In general, tension wire 550 may function as a pullwire that can be used to deflect coil 548 and, thus, catheter shaft 520.A biasing member 552 may also be coupled to coil 548. Biasing member 552may take the form of a ribbon, which may result in planar deflection ofcatheter 512. In at least some embodiments, biasing member 552 may havea width that is sufficiently large so as to prevent or reduce non-planarbuckling thereof during deflection of catheter 512. In general, biasingmember 552 may be configured to bias catheter shaft 520 into astraightened configuration. Accordingly, when pulling forces arereleased from tension wire 550, biasing member 552 may shift cathetershaft 520 from a deflected configuration to a generally straightenedconfiguration. Wire 550 may be attached to member 552 and extend througha tube 554 to a position accessible to a clinician.

The use of a coiled deflection member 548 may be desirable for a numberof reasons. For example, coil 548 may be a relatively simple and costeffective structure that can provide the desired deflectability tocatheter 512. In addition, coil 548 can be fabricated in a variety ofdifferent sizes including sizes appropriate for navigating catheter 512through relatively small body lumens and/or blood vessels.

The materials that can be used for the various components of catheter 12(and/or other catheters disclosed herein) and the various bodies and/ormembers disclosed herein may include those commonly associated withmedical devices. For simplicity purposes, the following discussion makesreference to tubular member 26 and other components of catheter 12.However, this is not intended to limit the devices and methods describedherein, as the discussion may be applied to other similar tubularmembers and/or components of tubular members or devices disclosedherein.

Tubular member 26 and/or other components of catheter 12 may be madefrom a metal, metal alloy, polymer (some examples of which are disclosedbelow), a metal-polymer composite, ceramics, combinations thereof, andthe like, or other suitable material. Some examples of suitable metalsand metal alloys include stainless steel, such as 304V, 304L, and 316LVstainless steel; mild steel; nickel-titanium alloy such aslinear-elastic and/or super-elastic nitinol; other nickel alloys such asnickel-chromium-molybdenum alloys (e.g., UNS: N06625 such as INCONEL®625, UNS: N06022 such as HASTELLOY® C-22®, UNS: N10276 such asHASTELLOY® C276®, other HASTELLOY® alloys, and the like), nickel-copperalloys (e.g., UNS: N04400 such as MONEL® 400, NICKELVAC® 400, NICORROS®400, and the like), nickel-cobalt-chromium-molybdenum alloys (e.g., UNS:R30035 such as MP35-N® and the like), nickel-molybdenum alloys (e.g.,UNS: N10665 such as HASTELLOY® ALLOY B2®), other nickel-chromium alloys,other nickel-molybdenum alloys, other nickel-cobalt alloys, othernickel-iron alloys, other nickel-copper alloys, other nickel-tungsten ortungsten alloys, and the like; cobalt-chromium alloys;cobalt-chromium-molybdenum alloys (e.g., UNS: R30003 such as ELGILOY®,PHYNOX®, and the like); platinum enriched stainless steel; titanium;combinations thereof; and the like; or any other suitable material.

As alluded to herein, within the family of commercially availablenickel-titanium or nitinol alloys, is a category designated “linearelastic” or “non-super-elastic” which, although may be similar inchemistry to conventional shape memory and super elastic varieties, mayexhibit distinct and useful mechanical properties. Linear elastic and/ornon-super-elastic nitinol may be distinguished from super elasticnitinol in that the linear elastic and/or non-super-elastic nitinol doesnot display a substantial “superelastic plateau” or “flag region” in itsstress/strain curve like super elastic nitinol does. Instead, in thelinear elastic and/or non-super-elastic nitinol, as recoverable strainincreases, the stress continues to increase in a substantially linear,or a somewhat, but not necessarily entirely linear relationship untilplastic deformation begins or at least in a relationship that is morelinear that the super elastic plateau and/or flag region that may beseen with super elastic nitinol. Thus, for the purposes of thisdisclosure linear elastic and/or non-super-elastic nitinol may also betermed “substantially” linear elastic and/or non-super-elastic nitinol.

In some cases, linear elastic and/or non-super-elastic nitinol may alsobe distinguishable from super elastic nitinol in that linear elasticand/or non-super-elastic nitinol may accept up to about 2-5% strainwhile remaining substantially elastic (e.g., before plasticallydeforming) whereas super elastic nitinol may accept up to about 8%strain before plastically deforming. Both of these materials can bedistinguished from other linear elastic materials such as stainlesssteel (that can also can be distinguished based on its composition),which may accept only about 0.2 to 0.44 percent strain beforeplastically deforming.

In some embodiments, the linear elastic and/or non-super-elasticnickel-titanium alloy is an alloy that does not show anymartensite/austenite phase changes that are detectable by differentialscanning calorimetry (DSC) and dynamic metal thermal analysis (DMTA)analysis over a large temperature range. For example, in someembodiments, there may be no martensite/austenite phase changesdetectable by DSC and DMTA analysis in the range of about −60 degreesCelsius (° C.) to about 120° C. in the linear elastic and/ornon-super-elastic nickel-titanium alloy. The mechanical bendingproperties of such material may therefore be generally inert to theeffect of temperature over this very broad range of temperature. In someembodiments, the mechanical bending properties of the linear elasticand/or non-super-elastic nickel-titanium alloy at ambient or roomtemperature are substantially the same as the mechanical properties atbody temperature, for example, in that they do not display asuper-elastic plateau and/or flag region. In other words, across a broadtemperature range, the linear elastic and/or non-super-elasticnickel-titanium alloy maintains its linear elastic and/ornon-super-elastic characteristics and/or properties.

In some embodiments, the linear elastic and/or non-super-elasticnickel-titanium alloy may be in the range of about 50 to about 60 weightpercent nickel, with the remainder being essentially titanium. In someembodiments, the composition is in the range of about 54 to about 57weight percent nickel. One example of a suitable nickel-titanium alloyis FHP-NT alloy commercially available from Furukawa Techno Material Co.of Kanagawa, Japan. Some examples of nickel titanium alloys aredisclosed in U.S. Pat. Nos. 5,238,004 and 6,508,803, which areincorporated herein by reference. Other suitable materials may includeULTANIUM™ (available from Neo-Metrics) and GUM METAL™ (available fromToyota). In some other embodiments, a superelastic alloy, for example asuperelastic nitinol can be used to achieve desired properties.

In at least some embodiments, portions or all of catheter shaft 20and/or tubular member 26 may also be doped with, made of, or otherwiseinclude a radiopaque material. Radiopaque materials are understood to bematerials capable of producing a relatively bright image on afluoroscopy screen or another imaging technique during a medicalprocedure. This relatively bright image aids the user of catheter 12 indetermining its location. Some examples of radiopaque materials caninclude, but are not limited to, gold, platinum, palladium, tantalum,tungsten alloy, polymer material loaded with a radiopaque filler, andthe like. Additionally, other radiopaque marker bands and/or coils mayalso be incorporated into the design of catheter 12 to achieve the sameresult.

In some embodiments, a degree of Magnetic Resonance Imaging (MRI)compatibility is imparted into catheter 12. For example, catheter shaft20 and/or tubular member 26, or portions thereof, may be made of amaterial that does not substantially distort the image and createsubstantial artifacts (i.e., gaps in the image). Certain ferromagneticmaterials, for example, may not be suitable because they may createartifacts in an MRI image. Catheter shaft 20 and/or tubular member 26,or portions thereof, may also be made from a material that the MRImachine can image. Some materials that exhibit these characteristicsinclude, for example, tungsten, cobalt-chromium-molybdenum alloys (e.g.,UNS: R30003 such as ELGILOY®, PHYNOX®, and the like),nickel-cobalt-chromium-molybdenum alloys (e.g., UNS: R30035 such asMP35-N® and the like), nitinol, and the like, and others.

A sheath or covering (not shown) may be disposed over portions or all ofcatheter shaft 20 and/or tubular member 26 that may define a generallysmooth outer surface for catheter 12. In other embodiments, however,such a sheath or covering may be absent from a portion of all ofcatheter 12, such that tubular member 26 and/or catheter shaft 20 mayform the outer surface. The sheath may be made from a polymer or othersuitable material. Some examples of suitable polymers may includepolytetrafluoroethylene (PTFE), ethylene tetrafluoroethylene (ETFE),fluorinated ethylene propylene (FEP), polyoxymethylene (POM, forexample, DELRIN® available from DuPont), polyether block ester,polyurethane (for example, Polyurethane 85A), polypropylene (PP),polyvinylchloride (PVC), polyether-ester (for example, ARNITEL®available from DSM Engineering Plastics), ether or ester basedcopolymers (for example, butylene/poly(alkylene ether) phthalate and/orother polyester elastomers such as HYTREL® available from DuPont),polyamide (for example, DURETHAN® available from Bayer or CRISTAMID®available from Elf Atochem), elastomeric polyamides, blockpolyamide/ethers, polyether block amide (PEBA, for example availableunder the trade name PEBAX®), ethylene vinyl acetate copolymers (EVA),silicones, polyethylene (PE), Marlex high-density polyethylene, Marlexlow-density polyethylene, linear low density polyethylene (for exampleREXELL®), polyester, polybutylene terephthalate (PBT), polyethyleneterephthalate (PET), polytrimethylene terephthalate, polyethylenenaphthalate (PEN), polyetheretherketone (PEEK), polyimide (PI),polyetherimide (PEI), polyphenylene sulfide (PPS), polyphenylene oxide(PPO), poly paraphenylene terephthalamide (for example, KEVLAR®),polysulfone, nylon, nylon-12 (such as GRILAMID® available from EMSAmerican Grilon), perfluoro(propyl vinyl ether) (PFA), ethylene vinylalcohol, polyolefin, polystyrene, epoxy, polyvinylidene chloride (PVdC),poly(styrene-b-isobutylene-b-styrene) (for example, SIBS and/or SIBS50A), polycarbonates, ionomers, biocompatible polymers, other suitablematerials, or mixtures, combinations, copolymers thereof, polymer/metalcomposites, and the like. In some embodiments the sheath can be blendedwith a liquid crystal polymer (LCP). For example, the mixture cancontain up to about 6 percent LCP.

In some embodiments, the exterior surface of the catheter 12 (including,for example, the exterior surface of catheter shaft 20 and/or theexterior surface of tubular member 26) may be sandblasted, beadblasted,sodium bicarbonate-blasted, electropolished, etc. In these as well as insome other embodiments, a coating, for example a lubricious, ahydrophilic, a protective, or other type of coating may be applied overportions or all of the sheath, or in embodiments without a sheath overportion of catheter shaft 20 or other portions of catheter 12.Alternatively, the sheath may comprise a lubricious, hydrophilic,protective, or other type of coating. Hydrophobic coatings such asfluoropolymers provide a dry lubricity which improves guidewire handlingand device exchanges. Lubricious coatings improve steerability andimprove lesion crossing capability. Suitable lubricious polymers arewell known in the art and may include silicone and the like, hydrophilicpolymers such as high-density polyethylene (HDPE),polytetrafluoroethylene (PTFE), polyarylene oxides,polyvinylpyrolidones, polyvinylalcohols, hydroxy alkyl cellulosics,algins, saccharides, caprolactones, and the like, and mixtures andcombinations thereof. Hydrophilic polymers may be blended amongthemselves or with formulated amounts of water insoluble compounds(including some polymers) to yield coatings with suitable lubricity,bonding, and solubility. Some other examples of such coatings andmaterials and methods used to create such coatings can be found in U.S.Pat. Nos. 6,139,510 and 5,772,609, which are incorporated herein byreference.

In addition to variations in materials, various embodiments ofarrangements and configurations are also contemplated for slots 34formed in flex tube 32 and for slots 44 a/44 b formed in flex body 28 inaddition to what is described above or may be used in alternateembodiments. Similar and/or analogous changes are also contemplated forribs 46 a/46 b (as well as other ribs disclosed herein) includingdesigns for differing rib geometries. For simplicity purposes, thefollowing discussion makes reference to slots 34. However, thisdiscussion may also be applicable to any of the cuts or slots disclosedherein as well as any of the ribs disclosed herein. For example, in someembodiments, at least some, if not all of slots 34 are disposed at thesame or a similar angle with respect to the longitudinal axis of tubularmember 26. As shown, slots 34 can be disposed at an angle that isperpendicular, or substantially perpendicular, and/or can becharacterized as being disposed in a plane that is normal to thelongitudinal axis of tubular member 26. However, in other embodiments,slots 34 can be disposed at an angle that is not perpendicular, and/orcan be characterized as being disposed in a plane that is not normal tothe longitudinal axis of tubular member 26. Additionally, a group of oneor more slots 34 may be disposed at different angles relative to anothergroup of one or more slots 34. The distribution and/or configuration ofslots 34 can also include, to the extent applicable, any of thosedisclosed in U.S. Pat. Publication No. US 2004/0181174, the entiredisclosure of which is herein incorporated by reference.

Slots 34 may be provided to enhance the flexibility of tubular member 26while still allowing for suitable torque transmission characteristics.Slots 34 may be formed such that one or more rings and/or tube segmentsinterconnected by one or more segments and/or beams that are formed intubular member 26, and such tube segments and beams may include portionsof tubular member 26 that remain after slots 34 are formed in the bodyof tubular member 26. Such an interconnected structure may act tomaintain a relatively high degree of torsional stiffness, whilemaintaining a desired level of lateral flexibility. In some embodiments,some adjacent slots 34 can be formed such that they include portionsthat overlap with each other about the circumference of tubular member26. In other embodiments, some adjacent slots 34 can be disposed suchthat they do not necessarily overlap with each other, but are disposedin a pattern that provides the desired degree of lateral flexibility.

Additionally, slots 34 can be arranged along the length of, or about thecircumference of, tubular member 26 to achieve desired properties. Forexample, adjacent slots 34, or groups of slots 34, can be arranged in asymmetrical pattern, such as being disposed essentially equally onopposite sides about the circumference of tubular member 26, or can berotated by an angle relative to each other about the axis of tubularmember 26. Additionally, adjacent slots 34, or groups of slots 34, maybe equally spaced along the length of tubular member 26, or can bearranged in an increasing or decreasing density pattern, or can bearranged in a non-symmetric or irregular pattern. Other characteristics,such as slot size, slot shape, and/or slot angle with respect to thelongitudinal axis of tubular member 26, can also be varied along thelength of tubular member 26 in order to vary the flexibility or otherproperties. In other embodiments, moreover, it is contemplated that theportions of the tubular member, such as a proximal section, or a distalsection, or the entire tubular member 26, may not include any such slots34.

As suggested herein, slots 34 may be formed in groups of two, three,four, five, or more slots 34, which may be located at substantially thesame location along the axis of tubular member 26. Alternatively, asingle slot 34 may be disposed at some or all of these locations. Withinthe groups of slots 34, there may be included slots 34 that are equal insize (i.e., span the same circumferential distance around tubular member26). In some of these as well as other embodiments, at least some slots34 in a group are unequal in size (i.e., span a differentcircumferential distance around tubular member 26). Longitudinallyadjacent groups of slots 34 may have the same or differentconfigurations. For example, some embodiments of tubular member 26include slots 34 that are equal in size in a first group and thenunequally sized in an adjacent group. It can be appreciated that ingroups that have two slots 34 that are equal in size and aresymmetrically disposed around the tube circumference, the centroid ofthe pair of beams (i.e., the portion of tubular member 26 remainingafter slots 34 are formed therein) is coincident with the central axisof tubular member 26. Conversely, in groups that have two slots 34 thatare unequal in size and whose centroids are directly opposed on the tubecircumference, the centroid of the pair of beams can be offset from thecentral axis of tubular member 26. Some embodiments of tubular member 26include only slot groups with centroids that are coincident with thecentral axis of the tubular member 26, only slot groups with centroidsthat are offset from the central axis of tubular member 26, or slotgroups with centroids that are coincident with the central axis oftubular member 26 in a first group and offset from the central axis oftubular member 26 in another group. The amount of offset may varydepending on the depth (or length) of slots 34 and can include othersuitable distances.

Slots 34 can be formed by methods such as micro-machining, saw-cutting(e.g., using a diamond grit embedded semiconductor dicing blade),electrical discharge machining, grinding, milling, casting, molding,chemically etching or treating, or other known methods, and the like. Insome such embodiments, the structure of the tubular member 26 is formedby cutting and/or removing portions of the tube to form slots 34. Someexample embodiments of appropriate micromachining methods and othercutting methods, and structures for tubular members including slots andmedical devices including tubular members are disclosed in U.S. Pat.Publication Nos. 2003/0069522 and 2004/0181174-A2; and U.S. Pat. Nos.6,766,720; and 6,579,246, the entire disclosures of which are hereinincorporated by reference. Some example embodiments of etching processesare described in U.S. Pat. No. 5,106,455, the entire disclosure of whichis herein incorporated by reference. It should be noted that the methodsfor manufacturing catheter 12 may include forming slots 34 in tubularmember 26 using these or other manufacturing steps.

In at least some embodiments, slots 34 may be formed in tubular memberusing a laser cutting process. The laser cutting process may include asuitable laser and/or laser cutting apparatus. For example, the lasercutting process may utilize a fiber laser. Utilizing processes likelaser cutting may be desirable for a number of reasons. For example,laser cutting processes may allow tubular member 26 to be cut into anumber of different cutting patterns in a precisely controlled manner.This may include variations in the slot width, ring width, beam heightand/or width, etc. Furthermore, changes to the cutting pattern can bemade without the need to replace the cutting instrument (e.g., blade).This may also allow smaller tubes (e.g., having a smaller outerdiameter) to be used to form tubular member 26 without being limited bya minimum cutting blade size. Consequently, tubular members 26 may befabricated for use in neurological devices or other devices where arelatively small size may be desired.

EXAMPLES

The invention may be further clarified by reference to the followingExamples, which serve to exemplify some of the embodiments, and not tolimit the invention in any way.

Example 1

It can be appreciated that a tubular member such as tubular member 26can most easily bend until the opposing wall surfaces on opposite sidesof slots 34 contact one another. For the purpose of this disclosure, thepoint where opposing wall surface of tubular member 26 on opposite sidesof slots 34 is termed the “crash point”. The crash point may define alimit to the radius of curvature for tubular member 26. The lower limitto the radius of curvature (RC) may be a function of the depth of slots34 (hereafter SD), the width of slots 34 (hereafter SW), and thedistance between adjacent slots 34 (hereafter D) as in the followingformula:

RC=SD+(SW/2)*[sin(D/SD)+(1+cos(D/SD)*tan(π/2−D/SD)]

An example flex body 28 and an example flex body 128 were modeled usingSOLID WORKS software (commercially available from Dassault SystemesSolidWorks Corp., Concord, Mass.). In the models, the SW was set to0.004 inches and the distance D was set to 0.006 inches. In the model,the radius of curvature was measured. The results are listed in Table 1.

TABLE 1 Radius of Curvature for Example Flex Bodies SD SW D RC Flex Body(inches) (inches) (inches) (inches) Flex Body 28 0.0094 0.004 0.0060.015452 Flex Body 128 0.0339 0.004 0.006 0.0564409It may be desirable to form flex bodies 28/128 so that they can achievea relatively small radius of curvature. This may allow flex bodies28/128 to navigate the anatomy. For example, flex bodies 28/128 arecontemplated that can achieve a relatively small radius of curvature sothat the device including such bodies can travel through the aorta andinto the renal artery (which may be offset nearly ninety degrees fromthe aorta). Factors such as variation in the slot depth, slow width,distance between adjacent slots, rib geometry, rib shape, rib spacing,etc. may be taken into account when constructing a flex body with thedesired features.

Example 2

An example deflectable ablation catheter was manufactured. The catheterincluded a flex body having a plurality of cuts formed therein andhaving a spine. An insulated but thermally conductive electrode wasattached to the catheter just distal of the flex body. A pull wire wasattached to the catheter at a distal end of the flex body.

The example catheter included a nitinol tubular member with fourcontinuous sections. The tubular member had an inner diameter of 0.032inches. A first section of the tubular member was attached to theelectrode and was 0.027 inches long. A 0.060 inch second sectionextended from the first section and included a round hole (0.010 inchesin diameter) where the pull wire was attached. A third section (takingthe form of a flex body) extended from the second section. The thirdsection was 0.396 inches long and included a plurality of cuts that were0.006 inches wide and longitudinally spaced 0.012 inches from oneanother. The beam length was stepped from proximal to distal 0.010,0.008, and 0.005 inches. The third section had two spines on oppositesides of the tubular member. Finally, a fourth section of the tubularmember extended from the third section. The fourth section was 0.060inches long and included two 0.010 inch glue holes for attaching thefourth section to a coupler. A 0.010×0.018 wire cave was formed in thefourth section.

The example catheter was used to treat a female Yorkshire pig. Thecatheter was advanced to the right renal artery of the animal via afemoral artery. The pull wire was used to deflect the catheter so thatthe electrode tip contacted the luminal surface of the artery and powerwas supplied to the electrode with an ablation controller. Thedeflection mechanism was used to deflect the electrode tip to multiplelocations on all sides of the artery, allowing ablation at eachlocation.

It should be understood that this disclosure is, in many respects, onlyillustrative. Changes may be made in details, particularly in matters ofshape, size, and arrangement of steps without exceeding the scope of theinvention. This may include, to the extent that it is appropriate, theuse of any of the features of one example embodiment being used in otherembodiments. The invention's scope is, of course, defined in thelanguage in which the appended claims are expressed.

What is claimed is:
 1. A deflectable medical device, comprising: acatheter shaft having a distal end; an ablation electrode disposed atthe distal end; a deflection mechanism coupled to the catheter shaft,the deflection mechanism including a deflection body and a pull wirecoupled to the deflection body; wherein the deflection body has alongitudinally-extending furrow formed therein; and a flex memberdisposed adjacent to the deflection mechanism.
 2. The deflectablemedical device of claim 1, wherein the deflection body includes a firstlongitudinally-extending spine and wherein a first group of slots areformed in the deflection body and define a first group of ribs.
 3. Thedeflectable medical device of claim 2, wherein the first spine has aconstant width.
 4. The deflectable medical device of claim 2, whereinthe first spine is tapered.
 5. The deflectable medical device of claim2, wherein the first spine includes a first portion having a firstwidth, a second portion having a second width, and a third portiondisposed between the first portion and the second portion and having athird width that is less than both the first width and the second width.6. The deflectable medical device of claim 2, wherein the deflectionbody includes a second longitudinally-extending spine and wherein asecond group of slots are formed in the deflection body and define asecond group of ribs.
 7. The deflectable medical device of claim 6,wherein the first longitudinally-extending spine and the secondlongitudinally-extending spine are positioned on opposite sides of thedeflection body.
 8. The deflectable medical device of claim 1, whereinthe flex member is attached to a distal end of the deflection body. 9.The deflectable medical device of claim 1, wherein the flex memberincludes a tubular member having a plurality of slots formed therein.10. The deflectable medical device of claim 1, wherein the pull wire isdisposed within the furrow.
 11. The deflectable medical device of claim1, wherein the deflection body includes a second furrow, and furthercomprising a second pull wire disposed within the second furrow.
 12. Thedeflectable medical device of claim 1, wherein the deflection body isconfigured to have a preferred bending direction.
 13. The deflectablemedical device of claim 1, wherein the deflection body is configured tohave more than one preferred bending direction.
 14. A deflectablemedical device for ablating a renal artery nerve, the medical devicecomprising: a catheter shaft including a proximal shaft portion, adeflection body coupled to the proximal shaft portion, a flex membercoupled to the deflection body, and an ablation member coupled to theflex member; wherein the deflection body includes a firstlongitudinally-extending spine, a second longitudinally-extending spine,a first set of ribs disposed between the first spine and the secondspine, and a first furrow disposed along the first set of ribs; anactuation member coupled to the deflection body, the actuation memberbeing configured to shift the catheter shaft between a firststraightened configuration and a second curved configuration; andwherein the actuation member is disposed within the first furrow. 15.The medical device of claim 14, wherein a second set of ribs is definedin the deflection body that is disposed between the first spine and thesecond spine and positioned on an opposite side of the deflection body,and wherein a second furrow is disposed along the second set of ribs.16. The medical device of claim 15, further comprising a secondactuation member, wherein the second actuation member is disposed withinthe second furrow.
 17. The medical device of claim 14, wherein the flexmember includes a tubular member having a plurality of slots formedtherein.
 18. The medical device of claim 14, wherein the deflection bodyis configured to have a preferred bending direction.
 19. The medicaldevice of claim 14, wherein the deflection body is configured to havemore than one preferred bending direction.
 20. A deflectable medicaldevice, comprising: a catheter shaft having a distal end; an ablationelectrode disposed at the distal end; a deflection mechanism coupled tothe catheter shaft, the deflection mechanism including a support coil, abiasing member, and a pull wire; wherein the deflection mechanism isconfigured to shift the catheter shaft between a first straightenedconfiguration and a second curved configuration; and a tubular memberdisposed adjacent to the deflection mechanism, the tubular member havinga plurality of slots formed therein.